Occupational stress on muscular-skeletal systems is a common enemy to health and productivity. Use of ergonomically designed tools is especially important to reduce the incidents of debilitating injuries to joints, fatigue of muscles, as well as injuries to other connective tissues and even nerves (e.g., carpal-tunnel syndrome). Improperly designed hand-held power tools such as drills, grinders, sanders, saws, etc. are typically heavy with unbalanced designs. In turn, typical users, such as those in the construction trades, often need to use such heavy, unbalanced power tools at odd angles and as a result, users put significant stress on key joints such as the wrist, elbow, and shoulder.
In the case of power drills and the like, a user not only must deal with the weight of said power tool, which usually is disposed in a pistol-like shape, but also must deal with fighting the torque generated by the power tool against the user's wrist.
One known attempt to address these issues with regard to power drills is documented in U.S. Pat. No. 5,445,479 to Hillinger (Hillinger). Hillinger discloses an electrically energized hand drill that departs from the traditional “pistol” type of drill and provides hand and lower forearm support to attempt to relieve physical stress on the user. However, the orientation of the aforementioned added support is such that if a user is drilling horizontally into a surface, the user must hold the drill such that the longitudinal axis formed by the curled fingers of the gripping hand is orthogonal to the ground. This is because the lower forearm support is a single rod (with or without padding) that is fixed along the outer side of the user's lower forearm. If the user changes orientation of the drill away from a strict horizontal application, then the user will experience much added stress on portions of the arm and wrist that remain unsupported in these other positions. Furthermore, the Hillinger drill places most of the major components of the drill, including most weight-bearing components, such as the drill motor and battery, in the front of the drill assembly and more importantly in front of the user's hand and/or wrist. Moreover, the actual drill motor and drill bit are substantially within the same longitudinal axis of the user's wrist and forearm. This configuration translates into the need for a user to exert counter-torque as the drill operates, as well as the need for the user to exert more effort than should be necessary to accommodate the excessively front-loaded weight of the Hillinger drill with the user's arm muscles.
Other attempts to address these ergonomic issues include U.S. Pat. No. D326597 to Lee (Lee), which discloses a power wrench with a pistol grip that also includes a lower forearm support bar and strap to help a user support the power tool in a manner very similar to that used for the Hillinger drill. The Lee solution suffers from the same deficiency as the Hillinger drill.
In most existing art, the system for user gripping and manipulation of the power tool provides insufficient leverage to easily overcome the inconvenient weight distribution and power-tool-generated torque to adequately avoid worker body stress and injuries. It would be desirable to have a more-ergonomic system for a user to operate a power tool, while enhancing the leverage a user has over the motorized portion of the tool for control purposes.